Individual Duty

In February 1998, Osama bin Laden and Ayman al-Zawahiri co-signed a fatwa in the name of the World Islamic Front for Jihad Against Jews and Crusaders, which declared the killing of North Americans and their allies an "individual duty for every Muslim" to "liberate the al-Aqsa Mosque (in Jerusalem) and the holy mosque (in Mecca) from their grip".